Under rare circumstances, diesel engines can experience a phenomenon called runaway, where the engine uncontrollably exceed normal operating speeds.

For diesel trucks, the typical EGT averages around 788 degrees Fahrenheit for optimal performance. Exceeding this range can lead to issues like engine overheating and reducing fuel economy.

Runaway engine events occur when an uncontrolled amount of fuel is dumped into the cylinders. That could be diesel fuel, or it could be another combustible source like oil.